There are few temples you can visit. you can do 1. boating at nakki lake.
2. You can visit the wildlife sanctuary.
3. Try few treks. online you can get numbers of people who arrange trekking.
or you can simple do it on your own. but that would be risky.
4. Visit guru shikhar
5. If you are a bunch of people traveling then you can do night camping 6. visit dhuriya waterfalls.
7. Treak upto the toad rock.